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The paper presents a full-field strain analysis of the appearance/disappearance of twinned martensite in a Cu–Al–Ni single crystal subjected to thermal cycles. Localized Spectrum Analysis (LSA) was employed to process images of a checkerboard pattern preprinted on the sample's surface, enabling us to obtain strain maps with a suitable trade-off between strain resolution (2 × 1 0 − 4 ) and spatial resolution (0.26 mm). During the cooling of the initially austenitic sample, habit plane variants (HPVs) were identified from the in-plane components of their mean right strain tensor. The match between measured data and theoretical expectations enabled us to measure the stretch parameters associated with the cubic-to-orthorhombic transformation occurring in the material. Various deformation mechanisms were revealed by an analysis in the strain space. In particular, the process of martensite appearance during cooling appeared to be based on the coordinated activation of HPVs pairs whose strain levels globally compensate each other. Elastic strain gradients were also evidenced, highlighting the need for additional deformation to achieve kinematic compatibility at microstructure interfaces. Lastly, several thermal cycles were applied to the previously-trained sample, enabling us to quantify the level of spatio-temporal repeatability of the phase transformation. [Display omitted] [ABSTRACT FROM AUTHOR]

The present work proposes a metrological route for capturing spatially‐resolved ultra‐high‐speed kinematic full‐field data from high strain‐rate experiments and multi‐sensor camera technology. This paper focuses, from an application point of view, on highly resolved rotating mirror cameras, such as the Cordin‐580. This camera allows 78 frames of 8 megapixels to be recorded at up to 4 million frames per second (fps). The optical apparatus induces distortions that need to be taken into consideration. Distortions are modelled with Zernike polynomials and recovered using Digital Image Correlation (DIC) with a tailored synthetic speckle pattern. Effective displacements can then be quantitatively obtained with subpixel precision. After an assessment of the calibrated camera performance, this methodology is used to record, at 480,000 fps, the fracture of a pre‐notched sample subjected to an inertial impact test. The kinematic fields obtained quantitatively captured the events occurring during the test, such as the compression wave and the induced Poisson effect, the Mode‐I crack initiation and the shear strain concentration at the notch tip. The achievement of a DIC displacement and strain random error of, respectively, 5 μm (0.15 pixels) and 2 mm m−1, combined with a high spatio‐temporal sampling, provides a promising way for quantitatively analysing very fast transient and heterogeneous phenomena. [ABSTRACT FROM AUTHOR]